channels for multiple SSIDs on the same device

[RickS03]

I've got an old Cisco 891 with two SSIDs configured. 

Both SSIDs are assigned to Dot11Radio0 and Dot11Radio1

Right now, it looks like Dot11Radio0 is on one channel: 

channel 2462

and Dot11Radio1 is on a different channel:

channel 5240

I'm wondering what the best practice is. Should each SSID be assigned to a different channel? 
In other words, if there are two SSIDs assigned to dot11radio0, should they both be assigned the same channel, or different ones? 

[Leo Laohoo]

Won't make a difference what channels each SSID is assigned to.
The most important thing is the 2.4 Ghz because the most "congested" WiFi band is the 2.4 Ghz.
It is best to do a scan of the 2.4 Ghz. If it is too busy, then powering down the 2.4 Ghz will help.

[pieterh]

basically

+ same device

+ same radio

+ multiple SSID's

-> all SSID's ,on this radio will be on the same channel

(one channel per radio), only when using 40MHz or 80MHz , multiple channels are used on the same radio